java - Mock a constructor with parameter

Question

I have a class as below:

public class A {
    public A(String test) {
        bla bla bla
    }

    public String check() {
        bla bla bla
    }
}

The logic in the constructor A(String test) and check() are the things I am trying to mock. I want any calls like: new A($$$any string$$$).check() returns a dummy string "test".

I tried:

 A a = mock(A.class); 
 when(a.check()).thenReturn("test");

 String test = a.check(); // to this point, everything works. test shows as "tests"

 whenNew(A.class).withArguments(Matchers.anyString()).thenReturn(rk);
 // also tried:
 //whenNew(A.class).withParameterTypes(String.class).withArguments(Matchers.anyString()).thenReturn(rk);

 new A("random string").check();  // this doesn't work

But it doesn't seem to be working. new A($$$any string$$$).check() is still going through the constructor logic instead of fetch the mocked object of A.

Answer 1

The code you posted works for me with the latest version of Mockito and Powermockito. Maybe you haven't prepared A? Try this:

A.java

public class A {
     private final String test;

    public A(String test) {
        this.test = test;
    }

    public String check() {
        return "checked " + this.test;
    }
}

MockA.java

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.equalTo;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(A.class)
public class MockA {
    @Test
    public void test_not_mocked() throws Throwable {
        assertThat(new A("random string").check(), equalTo("checked random string"));
    }
    @Test
    public void test_mocked() throws Throwable {
         A a = mock(A.class); 
         when(a.check()).thenReturn("test");
         PowerMockito.whenNew(A.class).withArguments(Mockito.anyString()).thenReturn(a);
         assertThat(new A("random string").check(), equalTo("test"));
    }
}

Both tests should pass with mockito 1.9.0, powermockito 1.4.12 and junit 4.8.2